Supplementary Material for: The association between surgical patient selection and hospital variation in failure to cure in esophageal cancer surgery. A nation-wide cohort study.

Introduction; Failure to cure describes: 1)non-resectional(‘open-close’) surgery, 2)non-radical surgery(R1-R2) and/or 3)postoperative mortality. This study aims to investigate whether hospitals offering surgery to a large proportion of patients have higher failure-to-cure rates than hospitals operating fewer patients.
Methods; From the Netherlands Cancer Registry, all cT1-cT4a/cTx-any cN-cM0 esophageal cancer patients diagnosed in 2015-2018 were included. For each center, the expected(E) proportion of patients undergoing surgery was established and divided by the observed(O) proportion. Hospitals were categorized into three groups: 1. hospitals treating relatively many patients with surgery, 2. average hospitals and 3. hospitals treating relatively few patients with surgery. Multilevel multivariable regression investigated the association between these hospital groups and failure to cure.
Results; Some 3,437(53.2%) of 6,457 patients underwent surgery, ranging from 45-64% among 16 hospitals. The failure-to-cure rate was 15.0%(hospital variation[4.6-23.7%]). After categorizing, 1,003 patients underwent surgery in hospitals with low surgery rates (O/E ratio54%). Failure-to-cure rates were 16.8%, 12.2% and 14.0%, respectively. This was non-significant in multilevel analyses (aOR:0.63, 95%CI:0.38-1.05; aOR:0.76, 95%CI:0.46-1.24).
Discussion/Conclusion; Failure-to-cure rates were similar in hospitals with a high surgery rate and hospitals with a low rate. Increasing the proportion of patients undergoing a resection may offer more patients a chance for cure.

引言；治愈失败的定义包括：1)非切除性（开-闭）手术，2)非根治性手术（R1-R2）以及/或3)术后死亡率。本研究旨在探讨提供手术给大量患者入院治疗的医院是否比治疗患者数量较少的医院具有更高的治愈失败率。
方法；从荷兰癌症登记处，纳入了2015-2018年间诊断的所有cT1-cT4a/cTx-任何cN-cM0食管癌患者。对于每个中心，确定了预期（E）接受手术的患者比例，并将其除以观察（O）比例。医院被分为三类：1.治疗相对较多患者的手术医院，2.平均医院，以及3.治疗相对较少患者的手术医院。多级多变量回归分析了这些医院群体与治愈失败之间的关联。
结果；在6,457名患者中，约有3,437名（53.2%）接受了手术，在16家医院中，手术比例在45-64%之间。治愈失败率为15.0%（医院变异[4.6-23.7%]）。在分类后，1,003名患者在手术率低的医院接受了手术（O/E比率为54%）。治愈失败率分别为16.8%、12.2%和14.0%。这在多级分析中不具有统计学意义（调整优势比：0.63，95%置信区间：0.38-1.05；调整优势比：0.76，95%置信区间：0.46-1.24）。
讨论/结论；手术率高的医院与手术率低的医院之间的治愈失败率相似。提高接受切除手术的患者比例可能为更多患者提供治愈的机会。